http://forums.leaflabs.com/topic.php?id=1629 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:05:06 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=1629&page=2#post-10512 Mon, 07 May 2012 20:24:25 +0000 crenn 10512@http://forums.leaflabs.com/ <p>A fuse (or a resettable fuse) would be a good precaution if you feel you need it. I wouldn't add a resistor as you'll also limit current to the circuit.</p> <p>If you're going to use a 3.3V external regulator, then as long as it's as close to 3.3V that you can make it (verify), just connect it to Vcc and ground. I have done this previously. I do know that powering the Maple from 5V (which is what my board provided to it) and adding in various other types of load to the system resulted in the voltage regulators on the mini being overloaded. </p> http://forums.leaflabs.com/topic.php?id=1629&page=2#post-10511 Mon, 07 May 2012 20:06:21 +0000 asterix 10511@http://forums.leaflabs.com/ <p>Or even better, 250mA fuse. </p> http://forums.leaflabs.com/topic.php?id=1629&page=2#post-10510 Mon, 07 May 2012 19:55:19 +0000 asterix 10510@http://forums.leaflabs.com/ <p>Thanks heaps guys. New boards arrived today (I bought 2 this time!!). Im going to get an external voltage regulator kit from Jaycar, trim the voltage down close to 3.3v, which should help. Maybe I should put a resistor in between my external vreg and my VIN on maple. Documentation says I need somewhere between 30 - 50 ma (Im only using SPI outputs) and rx/tx. I was powering my xbee shield and xbee series 1 through the maple as well and I suspect that might be adding to the load (55ma - can't find exact specs). But I think I'll do this through my external vreg.</p> <p>Do you think its worth adding a resistor into the mix just to be extra certain? </p> http://forums.leaflabs.com/topic.php?id=1629#post-10498 Sun, 06 May 2012 01:10:19 +0000 feurig 10498@http://forums.leaflabs.com/ <p>And if you replace the regulator try something like the 1117 series. i.e. LD1117S33. </p> http://forums.leaflabs.com/topic.php?id=1629#post-10443 Mon, 30 Apr 2012 20:00:39 +0000 asterix 10443@http://forums.leaflabs.com/ <p>I should have just gone up to the local electrical shop really and run a vreg into the maple that could blow before anything else. </p> http://forums.leaflabs.com/topic.php?id=1629#post-10442 Mon, 30 Apr 2012 19:59:04 +0000 asterix 10442@http://forums.leaflabs.com/ <p>I bought some new vregs for the other boards I had but afaik my soldering iron setup isn't really that great. SMD soldering needs some skills and tools that I don't have. </p> http://forums.leaflabs.com/topic.php?id=1629#post-10440 Mon, 30 Apr 2012 19:35:57 +0000 gbulmer 10440@http://forums.leaflabs.com/ <p>asterix - Oh that must be infuriating :-(</p> <p>Are you able to remove the regulator, and try to solder on a new one? </p> http://forums.leaflabs.com/topic.php?id=1629#post-10439 Mon, 30 Apr 2012 18:16:35 +0000 asterix 10439@http://forums.leaflabs.com/ <p>Sorry forgot to add, I had my multi-meter on the vin &amp; gnd terminals on the maple after the lights didn't come on. Then smokey! I guess that would've have sealed the deal. </p> http://forums.leaflabs.com/topic.php?id=1629#post-10437 Mon, 30 Apr 2012 17:40:17 +0000 asterix 10437@http://forums.leaflabs.com/ <p>Thanks gbulmer. You're always very helpful and explain things quite well.<br /> Although afaik now I have yet another blown board!!!!</p> <p>- I powered up the unit using 9v external battery. Unity worked fine.</p> <p>- I patched in my xbee (vcc, gnd, rx2,tx2), and array of shiftbrite leds (spi pins in maple, v+ &amp; gnd to the same battery powering the maple) and uploaded a sketch via usb power (no external power)</p> <p>- The first shiftbrite led in my shiftbrite array lit up!!! That has never happened before using usb power! For that to light up I must be getting 7.2v out of the VIN rail or the shiftbrite won't light up. Im pretty sure this shouldn't be happening.</p> <p>- Each shiftbrite chip draws up to 800ma. So rather than pushing my luck I disconnected usb and powered up the units using external power (9v).</p> <p>- Everything appeared to be working ok. Xbee receiving data, lights on in my shiftbrite array. I disconnected the xbee and shiftbrite array to upload any sketches.</p> <p>- I changed to a new rechargable battery (multi reads the battery at closer to 10v).<br /> - Had everything completely disconnected (including spi pins)<br /> - vin &amp; gnd to battery and SMOKEY VREG!!!!!</p> <p>I don't know seriously I've blown too many of these boards, I've spent probably close to $600 on maples with postage added in, and I'm a bit deflated right now. </p> http://forums.leaflabs.com/topic.php?id=1629#post-10429 Mon, 30 Apr 2012 09:29:42 +0000 jessb 10429@http://forums.leaflabs.com/ <p>Hey guys,</p> <p>gbulmer is, as usual, totally correct; the power regulation on Maple Mini r3 is the same as r2, but "officially" from now on it only supports up to 5V. As before you should still be able to power it from higher voltages as long as you're not pulling too much current, according to the calculations gbulmer provided. </p> <p>And no, it's not a knock off, seeed is an official LeafLabs distributor! Boards should be trickling back into stock at other distributors in the next couple weeks.</p> <p>(Also woops, sorry for not pushing the updated docs into the repo. will do that asap.) </p> http://forums.leaflabs.com/topic.php?id=1629#post-10423 Mon, 30 Apr 2012 06:03:39 +0000 gbulmer 10423@http://forums.leaflabs.com/ <p>asterix - The constraint is the voltage regulator. This regulates the voltage down to 3.3V from whatever you put into it. It acts like a variable resistor, and converts the excess power into heat, and it has a limited ability to get rid of the heat. If the heat can't be removed fast enough, it will overheat and, if you are lucky, shut itself down (and come back on when it has cooled enough), or be damaged. </p> <p>AFAIK, the change to the silk screen is because several people damaged the voltage regulator, but the regulator has not changed. </p> <p>The link provided by ala42 is to LeafLabs statement that that voltage regulator can dissipate 0.37W maximum (it should be a <strong>Microchip MCP1703</strong>), when running at an ambient temperature of 25C. </p> <p>You might want to be conservative, allow a bit of headroom, or a warmer environment and derate it to 0.3W, which represents an ambient of roughly 50C. </p> <p>So it you use a 9V power supply, it will have to convert the power to heat, and it must not be driven above, say 300mW, so<br /> power = voltage * current, and it must be &lt; 300mW<br /> = (9-3.3) * current = 5.7V * current &lt; 300mW<br /> current &lt; 52.6mA</p> <p>Looking at the ST Micro datasheet for the STM32F103xB (i.e. the generic part on the Maple Mini),<br /> (At <a href="http://www.st.com/internet/mcu/product/189782.jsp" rel="nofollow">http://www.st.com/internet/mcu/product/189782.jsp</a>, document DS5319: <a href="http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00161566.pdf)" rel="nofollow">http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00161566.pdf)</a></p> <p>Section "5.3.5 Supply current characteristics" says the maximum current, running at 72MHz, when "All I/O pins are in <strong>input</strong> mode".</p> <p>50mA = "Table 13. Maximum current consumption in Run mode, code with data processing running from Flash" with "External clock(2), all peripherals enabled" "All I/O pins are in <strong>input</strong> mode" at 85C.<br /> 36mA = "Table 17. Typical current consumption in Run mode, code with data processing running from Flash" with "External clock", "All peripherals enabled (though it says add 0.8mA for each ADC)" "All I/O pins are in <strong>input</strong> mode" at 25C.</p> <p>Note these values are with all pins set to be <strong>digital inputs</strong>, and tied to ground or Vdd, so they are not driving any current, not even the pin 13 LED.</p> <p>Bottom line, a Microchip MCP1703 regulator *should* run from 9V, providing the MCU isn't driving much current (WAG &lt;10mA) through output pins.</p> <p>A better approach would be to use a 5V power supply. Doing the power calculation again<br /> (5-3.3) * current &lt; 300mW<br /> 1.7 * current &lt; 300mW<br /> current &lt; 176mA</p> <p>(NB: If that regulator is one of the other common SOT23 parts, then its maximum power dissipation might be even lower, and hence its safe current supply capability lower.)</p> <p>(FULL DISCLOSURE: I am NOT a member of LeafLabs staff). </p> http://forums.leaflabs.com/topic.php?id=1629#post-10422 Mon, 30 Apr 2012 05:55:56 +0000 asterix 10422@http://forums.leaflabs.com/ <p>I hope its not a knock off. </p> http://forums.leaflabs.com/topic.php?id=1629#post-10420 Mon, 30 Apr 2012 03:40:40 +0000 asterix 10420@http://forums.leaflabs.com/ <p>I got it frm seeeduino<br /> It. says r3 on the unit. they had 80 units in stock. <a href="http://www.seeedstudio.com/depot/maple-mini-p-861.html?cPath=132_137" rel="nofollow">http://www.seeedstudio.com/depot/maple-mini-p-861.html?cPath=132_137</a>. image is different to the unit. </p> http://forums.leaflabs.com/topic.php?id=1629#post-10419 Mon, 30 Apr 2012 01:14:31 +0000 crenn 10419@http://forums.leaflabs.com/ <p>I haven't heard of any r3 Mini, nor does the GitHub have anything about r3. Where did you get your maple mini? I'd say 9v should be ok generally, as long as you don't put too much on the 3.3v rail </p> http://forums.leaflabs.com/topic.php?id=1629#post-10418 Mon, 30 Apr 2012 00:37:26 +0000 asterix 10418@http://forums.leaflabs.com/ <p>Yeah seen that. as i said normal units clearly say max 16v. this unit says max5v. couod i possibpy have a new revision that is not listed on the website? The vregs appear to be different too. </p>